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  1. #1
    Join Date
    May 2013
    Posts
    22

    Is Too Simple possible for Tool Height

    A new build CNCRP, Mach3, EthernetSS and PMDX126.

    I am configuring my Z for setting tool height and realized I had previously installed a hard mechanical limit switch wired to the E-stop (trips both high and low). Yes I do have to manually move it off when it over travels but I hope this will eventually be rare with good code and working soft limits.

    Why couldn't I just use a block of known height, connected to this circuit, and run the tool down till it E-stops and enter into Mach3 the height or the measured distance (which should be a constant after a few tries). The block could go on the table or the work piece and have a hard rubber section for some spring, the top soft metal. Once you pull the block the E-stop would be gone. I know I have plenty i/o with the SStepper but this still seems very easy... too easy? Am I over looking some conflict(s). Thanks Edward

  2. #2
    Join Date
    Jan 2013
    Posts
    306
    Check out one of the many auto zero scripts.
    They work great.

  3. #3
    Join Date
    Mar 2003
    Posts
    35538
    First, you should have your limit switches wired to the limit switch inputs. They'll pretty much work the same way they do now, but you'll be able to jog off of them.

    Using a limit switch to set your zero will not work well. After the switch is triggered, the Z axis still has to slow down to a stop, so you'll never really know exactly where your Z zero is.
    And when you come out of Estop, most times your steppers will move a small amount, so you'll never realy have a repeatable zero.

    As the previous poster said, set up an auto zero plate and use an Auto zero script. It shouldn't take long, and will give you an extremely accurate method of setting Z zero.
    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)

  4. #4
    Join Date
    May 2013
    Posts
    22
    Thanks, Just the input I needed, what previous poster were you referring to using the auto zero script.

  5. #5
    Join Date
    May 2013
    Posts
    22
    Got it going today with touch plate via BOB pin and Mach Script, works great, took 9 hrs but needed to confirm a lot of BOB parameters, make a plate and firm up all my grounds. Thanks again

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